Burglar alarm and signal system.



G. M. WILLIS. BURGLAE ALARM AND SIGNAL SYSTEM.

APPLICATION FILED DEG.11, 1906.

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UNITED STATES PATENT ornion.

GEORGE M. WILLIS, OF CHICAGO, ILLINOIS.

BURGLAB ALARM AND SIGNAL SYSTEM.

To all whom it may concern:

Be it known that I, Gnonen 11 1. WILLIs, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Burglar Alarm and Signal Systems, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to alarm systems, particularly to burglar alarm systems, its object being to provide improved circuit and controlling instrument arrangements therefor.

Burglar alarm circuits usually extend from a central station to a building to be protected, and these circuits are usually normally closed circuits containing a fixed amount of resistance, and at the central station is provided an instrument for con trolling the alarm signaling circuits, the adjustment of the instrument being such that it will be actuated to cause operation of alarm circuits when the resistance in the main circuit is either diminished or increased beyond a certain set value. In these prior systems also direct current is employed. Where resistance and direct current are employed, however, it is a very easy matter to interfere with the circuits, as the resistance thereof can easily be measured as also the current flow and the circuits so tampered with that a building could be entered without causing operation of the alarm at the central station.

In my improved system I utilize alternating or pulsating current, and in place of resistance I provide impedance or reactance in the line, and at the central station a suit able controlling instrument is provided for controlling the alarm and signaling circuits. Under normal conditions there is a certain amount of impedance or reactance included in the circuit during which time the instrument at the central station is in a neutral position and the signal and alarm circuits inoperative. Upon either increase or decrease of impedance in the circuits, the

instrument becomes effective to close the alarm and signal circuits, thus giving any desired signals at the central station. It is a very difficult matter to measure impedance or current flow in a system thus Specification of Letters Patent.

Application filed December 11, 1906.

Patented April 20, 1909.

Serial No. 347,308.

equipped, and tampering with circuits to revent actuation of central station alarms ecomes almost impossible.

The exact arrangement of the mechanism and circuits of my system will be best understood by reference to the accompanying drawing which diagrammatically represents a central station and three main circuits leading therefrom, each circuit terminating at the central station in a controlling and alarm outfit.

Each central station outfit comprises a controlling instrument I, a controlling switch S, a signal key K, an indicating and circuit controlling drop D, and a test switch T. Each controlling instrument has a coil 1 and a needle 2 whose deflection is controlled by the amount of current flow through the coil. The needle carries contacts 3 and 4, and to the left of the needle is a contact arm 5 having a contact point 6 and adjustably pivoted at 7, while to the right of the needle is a contact arm 8 having a contact point 9 and adjustably pivoted at 10. A scale 11 is provided for the needle and contact arms. The switch S has the arm 12 pivoted centrally at 13, the ends normally engaging the contacts 14 and 15, respectively, while contacts 16 and 17 to the right of contacts 14 and 15 are adapted to be engaged by the respective ends of the arm upon rotation thereof. The contacts 14 and 16 are connected together and connected through conductor 18 with the contact arm 5, while contacts 15 and 17 are connected together and through conductor 19 with contact arm 8. The key K has the actuating spring 20, the normal contact spring 21, and the alternating contact spring 22, the spring 20.being provided with a button 23. tromagnet 24, the shutter drop 25, the armature 26, and the latch arm 27 extending forwardly therefrom, normally holding up the drop 25. The contacts 28 and 29 are arranged to be electrically connected through the drop upon release thereof when the electromagnet is energized. The testing key T comprises the switch arm 30 and the contact 81, the switch being normally open.

The central station circuits include the bus bar 32 connected through conductor 32with one terminal of an alternating current generator G whose other terminal connects to ground through conductor 33. There are also run through the central station bus bars The indicating drop D has the elec- 34, 35 and 36, bus bar 34 being connected with ground through conductor 34, while bus bar 35 is connected with one terminal of the secondary winding 37 and bus bar 36 is connected to one terminal of the direct current generator 0. The other terminal of the secondary winding 37 connects with ground through conductor 33, this secondary winding being inductively supplied with current from the primary winding 38 connected between the terminals of the generator G. The other terminal of the direct current generator-C is also connected to ground, through conductor 33. One terminal of the instrument coil 1 for each central station outfit connects bus bar 32 through a conductor 39, while the other terminal of each coil connects through conductor 40 with the normal contact spring 21 of the key K whose alternating contact spring 22 connects through conductor 41 with bus bar 36 and whose actuating spring 20 connects through conductor 42 with contact 31 of the test switch. One terminal of the winding of the electromagnet 24 connects through conductor 43 with the switch arm 12, and the other terminal of this winding connects through conductor 44 with bus bar 34. The instrument needle 2 is connected with bus bar 35 through conductor 45, and the switch arm 30 of the test switch connects through conductor 46 with conductor 44 and thence with the ground bus bar 34, conductor 46 including a resistance 7". Contact 29 connects with bus bar 36 through conductor 47, while contact 28 connects with ground bus bar 34 through conductor 48 which conductor includes a resistance 1" and a lamp Z. The terminals of each indicating drop wind ing also connect through conductors 49 and 50 with the terminals of a winding 51 for the indicating and alarm drop A, each of these drops having a shutter drop 52, an armature 53, and a latch arm 54 for normally holding up the shutter. Each latch arm has a contact 55 disposed below a common bus bar 56 which connects with bus bar 36 through conductors 57 and 47 the conductor 57 including a bell 58. The main line extends from the contact 31 and eventually connects with ground at 9. Each line includes an adjustable reactance 59 which may be comprised in an integral arrangement or which may be formed of individual adjustable reactances, and this reactance is associated with the circuits for doors, windows and so on in the building to be protected which are to be opened or closed and which control the contacts c normally included in the main circuit. Adjustable reactance or reactances 60 are also provided, associated with the circuits for permanent partitions, screens and so on. In each main circuit there is also a non-inductive resistance 61 bridged by a bell 62,

the main circuit, the bell, however, being adjusted to be irresponsive to the alternating current flow. The resistance, however, is sufficient to cause direct current sent over the line to flow in greater part through the signal bell. The reactance 59 is also adapted to be bridged or short circuited-by a switch 63, this switch being closed during the day time when it is desired to use the doors and Windows with which the reactance 59 is associated. 'A signal key 64 is also provided by means of wnich the main line may be opened.

The circuits and operation of the various parts can now be readily traced. At night time the switch 63 is open and the combined reactance in circuit, and the current flow will be as follows :from the alternating current generator G, through conductor 32, bus bar 32, through conductors 39, through coils 1 of the instruments, through conductors 40, springs 21 and 20 of the keys K, through conductors 42 into the main lines through reactances 60, through resistance 61, through reactances 59, through keys 64 and through house contacts 0 to ground. V-Jhen the entire reactance is in circuit, the adjustment of the station instrument is such that the needle will be in a midway position between the contact arms 5 and 8, the needle being preferably in a vertical posit on. Allowance is made for the ordinary fluctuations in current flow through the circuit, and the contact arms 5 and 8 are, therefore, so disposed that during such normal fluctuations they will not be engaged by the needle. Suppose now, that the circuit connected with the central station outfit at the right of the drawing is tampered with and the reactance increased. The result will be greater current flow and greater deflection of the needle to the right into engagement with contact arm 8. The following circuit will then immediately be closed: from grounded conductor 33, through secondary winding 37, through conductor 45, needle 12, contact arm 8, switch arm 12, conductor 43, winding of dro D, through conductor 44 to bus bar 34 an through conductor 34 to ground. The armature 26 will become attracted and the latch arm 27 raised to release the drop 25 which falls into engagement with the contacts 28 and 29, thereby causing closure 01 the following circuit: from generator 0, through bus bar 36, through conductor 47, contact 29, drop 25, contact 28, lamp Z, re sistance 7*, bus bar 34, conductor 34 and conductor 33 to the other terminal of generator C. The illumination of lamp Z is a signal to the operator that something is wrong with the line, and this lamp may be placed in any convenient position, a good position being behind the scale 11 which may be of glass, and thus the lamp will serve to illuminate the scale at the same time giving the signal to the operator. Upon such deflection of the needle there is also current flow 1 tral station as before, the deflection of the through the dro winding 51 bridged across the terminals 0 the drop winding 24, and the latch arm 54 being raised to carry contact 55 against the bus bar 56, circuit is closed through the alarm bell 58 as follows: from bus bar 36, through conductors 47 and 57, through bell 58, bus bar 56, contact 55 and latch arm 54 to ground and thence to the other side of the generator 0. The drops 25 and 52 when falling are also arranged to reveal the number of the corresponding main circuit, thus indicating to the operator which circuit is in trouble. When the drop 25, however, is mixed in with the other apparatus as shown, it is very difficult to be seen, and the drops A, therefore, are provided, these drops being mounted on a common board, the boarc and indicating shutters being suitably painted so that the number of the hne may be quickly ascertained. I "find that I can obtain good results by operating the 'enerator G at 60 cycles and 50 volts, but T'find that I cannot as efficiently utilize the 50-volt, 60-cycle current through the contacts of the controlling instrument, the reason being that after a certain number of engagements between the needle and contact arms, the contacts stick and become destroyed, I have been enabled to practically ehnnnate this by using alternating current at 100 volts and 60-cycles-that is, by increasing the voltage to cut down the current, and this 100 volts I obtain by the use of a transformer arrangement comprising a primary winding 38 fed from the generator G and the secondary winding 37.

As there is a possibility of the instrument needle sticking at its neutral point and. thus not being responsive to changes in the main circuit, the test switch T is provided for ascertaining whether the needle is operative or sticking. Upon closure of this switch, a local circuit flows as follows: from generator G, throughconductor 32, bus bar 32, conductor 39, instrument coil 1, conductor 40, key springs 21 and 20, conductor 42, contact 31 and arm 30 of switch T, resistance r and through conductors 46 and 44 to grounded bus bar 34and thence back to generator G. The resistance r is of such value that if the needle is not sticking, it will be deflected upon closure of the test switch, and if the needle does not move upon such closure, the operator knows that the instrument is defective and must be repaired or replaced. it upon tampering with the circuit the reactance had been decreased. or house contacts opened, then there would be diminished current flow or no current flow, and the needle would be deflected to the left into engagement with contact arm 5 and the path from the needle to the switch S would be through contact arm 5, conductor 18 and contact 14, but the same signals will be given at the connecdle merely indicating the nature of the changes in the main circuit.

in the morning, usually when business begins, the switch 63 must be closed to allow the doors and windows to be used. Afixed time, however, is set when the storekeeper or watcinnan actuates the key 64 to open the line, this being manifested. by the deflection of the needle to the left and actuation ofthc central station signals. The key 64, however, is opcrated to give a code signal, and, therefore, the alarm bells and lamps at the central station will be actuated a succession of times to distinguish from the alarm signal. The central station attendant in response to the signal rotates switch arm 12 into engagement with the contact 16 and away from contact 15, and the storekeeper or watchman closes key 64 and switch 63. Closing of switch 63 cuts the reactance 59 from circuit, and the increase current flow through the line will cause deflection of the needle into engagement with contact arm 8. Upon rotation of switch arm 12, however, contact arm 8 has become disconnected from the switch arm and circuit will not be closed through the central station signaling device. in the evening when the building is again to be locked up, the switch 63 must be closed to render the reactance 59 active. Prior to closing the switch, however, the storekeeper or watchman again gives a code signal by means of the key 64, in response to which the central station attendant restores the switch 12 to its normal position in engagement with contacts 14 and 15, and when the switch 63 is again opened, the needle will assume its normal or midway position, and the system is ready for alarm calls during the period through which the building is to be pro tected. In the same manner movement of arm 12 to engage contact 17 and to leave contact 14, will cause contact arm 5 to be disconnected from the signal circuit. It will be noted that normally the needle and switch arm 12 are vertical and that for the day position they are practically parallel and inclined to the right. The operator by noting these positions of these parts can then quickly determine the condition of the system. It is also desirable that the central station attendant be enabled to send signals to the building to be protected, this being accomplished by means of the key K. Upon depression of this key, the controlling instrument is disconnected from circuit, and the following circuit closes: from gene 'ator 0, through bus bar 36, conductor 41, key springs 22 and 20, conductor 42 and through the main line to ground and thence back to the other terminal of generator C. The direct current from generator C will in greater part flow through the bell 62 at the building on account of the high resistance 61, and signals may thus be sent to the subscriber who may answer if he desires by manipulation of his signal key 6%.

T he central station outfit for each line may be conveniently mounted on a board or any casing represented by the dotted lines 65, and owing to the arrangement of the various mechanisms all the contacts can be arranged to appear on the outside to be readily inspected, cleaned or repaired.

The use of alternating current and reactance in the line renders it very diflicult for any one to tampcrwith the system without destroying the balance and consequently causing an alarm, it being a very diificult matter to ascertain the value of the reactance or current flow through the line. The instrumentalities employed in this system and the circuit arrangements therefor are also extremely simple and compactly arranged, thus greatly reducing the maintenance and greatly increasing the eihciency and reliability.

1 do not wish to be limited to the precise arrangement shown and referred to, as changes may be readily made without departing from the scope of the invention. Instead of alternating current through the main line, pulsating current may be used, and instead of only react-ance, other resistance may be included in the line, thus oirering impedance to the flow of the alternating or pulsating current.

Having described my invention, I claim as new and desire to secure by Letters Patent:

1. In an alarm and signaling system, the combination of a normally closed main circuit connecting a central station with a substation to beprotected, a source of current for supplying the main circuit, a controlling instrument at the central station having a coil or winding included in said main circuit, a needle or switch arm adaptedto be deflected upon change in current flow through the winding, said needle or switch arm being connected with one terminal of said source, a contact at each side of the needle or switch arm adapted to be engaged thereby upon suflicient deflection thereof, switch mechanism connecting both contacts with the other terminal of said source, alarm and signaling mechanism included in said switch circuit, increase or decrease in the current flow through the main circuit causing corresponding deflection of the needle or switch arm into engagement with the corresponding contact whereby the circuit is closed through the alarm and signaling apparatus, said switch mechanism being adapted to be actuated to shift the control of the alarm and signaling apparatus circuit from both contacts to either one thereof.

2. In an alarm and signaling system, the combination of a normally closed main circuit connecting a central station with a substation to be protected, a source of current for supplying said main circuit, a controlling instrument connected in the main circuit, a deflecting needle or switch arm for the instrument, a contact at each side of the deflecting needle, a local circuit connected with said needle and normally with both contacts, to be controlled by either contact, variation in current flow through the main circuit causing corresponding deflection of the indi cating needle or switch arm into engagement with one of the contacts to close the local circuit, alarm and signaling apparatus included in the local circuit to be actuated upon closure thereof, and means for shifting the control of the local circuit from both contacts to either one of the contacts.

3. In an alarm and signaling system, the combination of a normally closed main circuit connecting a central station with a substation to be protected, a source of alternating current for supplying the circuit, a controlling instrument having a winding included in the main circuit, a movable switch arm controlled by the current flow through the winding, a contact for said switch arm adapted to be engaged thereby upon SllfllClGIlll movement thereof, a local circuit at the central station, alarm and signaling apparatusin said circuit, an independent source of higher voltage alternating current for supplying said local circuit, said local circuitbeing controlled by the switch arm and contact, reactance of a certain value normally included in the main circuit to allow normal current flow through the main circuit of a value insufficient to cause deflection of the needle into engagement with the contact, reduction of said reactance beyond a predetermined amount allowing suflicient current flow to deflect the switch arm into engagement with the contact whereby the local circuit is closed and the alarm and signaling apparatus at the central station actuated.

4. In an alarm and signaling system, the combination of a normally closed main circuit extending from a central station to a substation to be protected, a source of alternating current at the central station for supplying the main circuit, a controlling instrument at the central station having awinding included in said main circuit, a movable switch arm controlled by the current flow through said winding, a contact at each side of said switch arm, a local circuit at the central station, alarm and signaling mechanism included in said local circuit, a source of alternating current for said local circuit having higher voltage than the main source, said local circuit being controlled by the switch arm and contacts, and reactance in the main circuit having normally a fixed value which allows current flow through the main circuit and instrument winding to hold the switch arm in a neutral position between the contacts, increase or decrease of reactance in the circuit beyond a fixed limit causing a corresponding movement of the switch arm to engage one of said contacts to close the local circuit, thereby causing actuation of the alarm and signaling mechanism.

5. In an alarm and signaling system, the combination of anormally closed main circuit extending from a central station to a substation to be protected, a source of alternating current at the central station for supplying the main circuit, a controlling instrument at the central station having a winding included in said main circuit, a movable switch, arm controlled by the current flow through said winding, a contact at each side of said switch arm, a local circuit at the central station, alarm and signaling mechanism included in said circuit, a source of alternating current for said local circuit, said local circuit being controlled by the switch arm and contacts, reactance in the main circuit having normally a fixed value which allows current flow through the main circuit and instrument winding to hold the switch arm in a neutral position between the contacts, increase or decrease of reactance in the circuit beyond a fixed limit causing a corresponding movement of the switch arm to engage one of said contacts to close the local circuit, thereby causing actuation of the alarm and signaling mechanism, and means for connecting said local circuit with both contacts or with only one thereof.

6. In an alarm and signaling system, the combination of a normally closed main circuit extending from a central station to a substation to be protected, a source of current for supplying the main circuit, a controlling instrument at the central station having a winding included. in said circuit, a movable switch arm controlled by the current flow through said winding, a contact at each side of said switch arm to be engaged thereby to cause sufficient movement thereof, a local circuit at the central station of higher voltage than the main circuit and normally connected with said switch arm and with both contacts, alarm and signaling apparatus included in said local circuit, current controlling means included in the main circuit and normally adjusted so that the current flow through the winding of the instrument will hold the switch arm in a neutral position between the contacts, increase or decrease in current flow through the main circuit causing corresponding movement of the switch arm into engagement with one of the contacts to close the local circuit, means at the substation for rendering ineffective part of the circuit, controlling means whereby increased current flow through the main circuit will cause movement of the switch arm into engagement with the corresponding contact, and switching means at the central station for disconnecting the engaged contact from the local circuit.

i 7 In an alarm and signaling system, the combination of a main circuit connecting a central station with a substation to be protected, a source of current for supplying said central station, an instrument connected with the main circuit and controlled by the current flow therethrough, a movable switch arm for the instrument, a contact at each side of the switch arm to be engaged thereby upon sufficient movement thereof, said switch arm being normally in a neutral position between the contacts, a local circuit at the central station, alarm and signaling apparatus included in said local circuit, a source of current for said local circuit, one terminal of said local circuit being connected with the switch arm, and switch mechanism for connecting the other terminal of the local circuit either with both contacts or with only one thereof.

8, In an alarm and signaling system, the combination of a main circuit extending from a central station to a substation to be protected, a source of alternating current normally connected with said circuit, signal receiving apparatus at the substation irresponsive to alternating current flow, -a source of direct current at the central station, and switching means for disconnecting the alternating current source from the main circuit and for connecting therewith the source of direct current, said signal receiving apparatus at the substation being responsive to the direct current flow.

9. In an alarm and signaling system, the combination of a normally closed main circuit connecting a central station with a substation, a source of alternating current nor mally included in said main circuit, signal receiving a paratus at the substation connected wit the main circuit but irresponsive to alternating current flow therethrough, a source of direct current at the central station, and switching mechanism for disconnecting the alternating current source from the main circuit and substituting therefor the source of direct current, said signal receiving apparatus at the substation being responsive to direct current flow.

10. In an alarm and si naling system, the combination of a normally closed main circuit connecting a central station with a substation, a source of alternating current in cluded in said main circuit, a controlling instrument at the central station included in the main circuit, switch mechanism controlled by said instrument, a local circuit at the central station controlled by said switch mechanism, alarm and signaling apparatus in said local circuit, a transformer connected with the main circuit and supplying said 10- cal circuit, variation in current flow through the main circuit causing actuation of the instrument to operate its switching mechanism to control the local circuit, a source of direct current at the central station, switch 1 the source, and reactance of a certain value mechanism for connecting said source of di rect current with the main line, and a signal receiving device at the substation connected in the main circuit, said signal receiving device being irres onsive to alternating current flow throug the line but responsive to direct current flow through the main circuit.

11. In an alarm and signaling system, the combination of a normally closed main circuit connecting a central station with a substation, a source of alternating current at the central station, a source of direct'current at the central station, signal receiving means at the substation responsive only to direct current flow, a signal-receiving device at the central exchange responsive to alternating current flow, and switch mechanism at the central exchange for alternately connecting the signal-receiving mechanism at the central exchange in the main circuit and for con necting the direct current source with the main circuit to cause actuation of the signalreceiving means at the substation.

12. In an alarm and signaling system, the combination of a normally closed main circuit connecting a central station with a substation to be protected, a source of alternating current for supplying the main circuit, a controlling instrument having a winding included in said main circuit, a movable switch arm controlled by the current flow through said winding, contact mechanism controlled upon movement of said switch arm, a local circuit controlled by said switch mechanism, alarm and signaling apparatus in said local circuit, a transformer for supplying current to the local circuit, said transformer being connected with the source of alternating current to receive energy therefrom and to raise the voltage in the local circuit over that of 5 included in the main circuit, change in the value of said reactance causing change in the current flow through the main circuit to cause movement of the switch arm and actuation of the switch mechanism to cause current flow through the local circuit from said transformer.

13. In an alarm and signaling system, the combination of a normally closed main circuit connecting a central station with a substation to be protected, at source of alternating current for supplying the main circuit, a controlling instrument having a winding included in said main circuit, a movable switch arm controlled by the current flow through said winding, contact mechanism controlled upon movement of said switch arm, a local circuit controlled by said switch mechanism, alarm and signaling apparatus in said local circuit, a transformer for supplying current to the local circuit, said transformer being connected with the source of alternating current to receive energy therefrom and to raise the voltage in the local circuit over that of the source, and reactance of a certain value included in the main circuit, change in the value of said reactance causing change in the current flow through the main circuit to cause movement of the switch arm and actuation of the switch mechanism to cause cur rent flow through the local circuit from said transformer, said switch arm being included in said local circuit.

In Witness whereof, I hereunto subscribe my name this 7th day of December A. 1).,

GEORGE M. IVILLIS.

Witnesses CrrARLEs- J. SCHMIDT, GEORGE E. HIGHAM. 

